docs: def from_iso(cls, iso):
          """Retrieve the first datacenter id associated to an ISO."""
          result = cls.list({'sort_by': 'id ASC'})
          dc_isos = {}
          for dc in result:
              if dc['iso'] not in dc_isos:
                  dc_isos[dc['iso']] = dc['id']
  
          return dc_isos.get(iso)